Table 1.

Summary of kinetic constants for the SRX in tarantula muscle.

Incubationa	Chase	P1b	T1 (sec)	P2	T2 (sec)	P3	T3 (sec)	Nc
mantATP	ATP + ML-7	0.34 ± .02	23± 3	0.17 ± .02	278 ± 31	0.48 ± .03	1995 ± 231	22
mantADP	ADP	0.55 ± .03	6 ± 1	0.26 ± .02	27 ± 3	0.11 ± .03	193 ± 26	11
mantATP+ATPd	ATP	0.79 ± .02	9 ± 4			0.11 ± .02	54 ± 19	6
~Pe mantATP	ATP	0.48 ± .03	15 ± 2	0.22 ± .03	34 ± 5	0.23 ± .02	319 ± 29	13

^aThe first 2 columns give the nucleotides in the initial incubation and the chase solutions.

^bP1, P2 and P3 are the magnitudes and T1 T2 and T3 are the lifetimes for the first, second and third phases of the three-exponential function that was fit to the data; see Eq. 1, Methods.

^cErrors are standard errors of the mean for N^c observations.

^dThese data were fit adequately by a two-exponential fit.

^e~P signifies that the fibers were phosphorylated.